Effects of electrode size and placement on comfort and efficiency during low-intensity neuromuscular electrical stimulation of quadriceps, hamstrings and gluteal muscles

Background Neuromuscular electrical stimulation (NMES) may prevent muscle atrophy, accelerate rehabilitation and enhance blood circulation. Yet, one major drawback is that patient compliance is impeded by the discomfort experienced. It is well-known that the size and placement of electrodes affect the comfort and effect during high-intensity NMES. However, during low-intensity NMES the effects of electrode size/placement are mostly unknown. Therefore, the purpose of this study was to investigate how electrode size and pragmatic placement affect comfort and effect of low-intensity NMES in the thigh and gluteal muscles. Methods On 15 healthy participants, NMES-intensity (mA) was increased until visible muscle contraction, applied with three electrode sizes (2 × 2 cm, 5 × 5 cm, 5 × 9 cm), in three different configurations on quadriceps and hamstrings (short-transverse (ST), long-transverse (LT), longitudinal (L)) and two configurations on gluteus maximus (short-longitudinal (SL) and long-longitudinal (LL)). Current–density (mA/cm2) required for contraction was calculated for each electrode size. Comfort was assessed with a numerical rating scale (NRS, 0–10). Significance was set to p < 0.05 and values were expressed as median (inter-quartile range). Results On quadriceps the LT-placement exhibited significantly better comfort and lower current intensity than the ST- and L-placements. On hamstrings the L-placement resulted in the best comfort together with the lowest intensity. On gluteus maximus the LL-placement demonstrated better comfort and required less intensity than SL-placement. On all muscles, the 5 × 5 cm and 5 × 9 cm electrodes were significantly more comfortable and required less current–density for contraction than the 2 × 2 cm electrode. Conclusion During low-intensity NMES-treatment, an optimized electrode size and practical placement on each individual muscle of quadriceps, hamstrings and gluteals is crucial for comfort and intensity needed for muscle contraction.

Notes from the Field: The Construction of a Logistical Model for Sports-Related Injury Risk Assessment. A Cross-Sectional Pilot Study

Handball is a high-intensity contact sports activity characterized by repetitive movements, leading to sport-specific muscle patterns. However, at some stage, this pattern may turn into imbalance, predisposing athletes for injuries. The complexity of muscular interactions often makes it difficult to see a whole picture of an athlete’s postural disorders and assess them within the framework of his stereotyped movements. We attempted to find an association between the muscle pattern and the number of injuries in a limited group of handball players by constructing a static logistical model. The constructed decision table of the static logistical model included seven conditional attributes of the muscle imbalance as preconditions for injury development and one decision attribute representing the number of experienced injuries of 25 university handball players. The findings displayed a sport-specific pattern of muscle alignment in athletes without or only one injury. However, all players with repetitive injuries had unilateral m. gluteus maximus weakness. In the latter case, impaired core body musculature can lead to increased share forces and stress for the gluteus maximus muscle leading to weakness of this crucial dynamic stabilizer. The logistical model allowed defining muscle imbalance associated with sports-related injuries in a limited group of athletes.

Bladder paraganglioma: CT and MR imaging characteristics in 16 patients

Background Bladder paraganglioma (BPG) is a rare extra-adrenal pheochromocytoma with variable symptoms and easy to be misdiagnosed and mishandled. The aim of the study was to document the imaging features of BPG using computed tomography (CT) and magnetic resonance imaging (MRI). Patients and methods We retrospectively enrolled consecutive patients with pathology-proven BPG, who underwent CT or MRI examinations before surgery between October 2009 and October 2017. The clinical characteristics, CT, and MRI features of the patients were described and analysed. Results A total of 16 patients with 16 bladder tumours (median age 51 years, 9 females) were included. Among them, 13 patients underwent CT examinations and eight patients underwent MRI examinations preoperatively. Tumour diameters ranged from 1.6−5.4 cm. Most of the tumours grew into the bladder cavity (n = 11) with oval shapes (n = 10) and well-defined margins (n = 14). Intratumour cystic degeneration or necrosis (n = 2) was observed. Two lesions showed peripheral tissue invasion, suggesting malignant BPGs. All 13 lesions imaged with CT exhibited slight hypoattenuation and moderate to marked enhancement. Compared to the gluteus maximus, all lesions showed slight h yperintensity in T2-weighted images, hyperintensity on diffusion-weighted images (DWI), hypointensity on apparent diffusion coefficient maps, hyperintensity on T1-weighted images and a “fast in and slow out” enhanced pattern on contrast-enhanced MRI images. Conclusions BPGs are mostly oval-shaped, broadly-based and hypervascular bladder tumours with hypoattenuation on non-contrast CT, T2 hyperintensity, slight T1 hyperintensity compared to the muscle, marked restricted diffusion on DWI. Peripheral tissue invasion can suggest malignancy of the BPGs. All of these features contribute to preoperative decision-making.

Comparison of Muscle Density in Middle-Aged and Older Chinese Adults Between a High-Altitude Area (Kunming) and a Low-Altitude Area (Beijing)

Background and PurposeA high-altitude environment was known to have a negative effect on bone and lead to a higher incidence of hip fracture. However, the dependence of muscle composition on altitude is unclear. Thus, we aimed to compare muscle density and area in plateau and low altitude area and to determine the effect of the altitude on these outcomes.MethodsCommunity dwelling adults over 60 years old living in Beijing (elevation 50 m; 300 subjects,107 men and 193 women) or Kunming (elevation 2000 m; 218 subjects,83 men and 135 women) for more than 10 years were enrolled. Quantitative CT was performed in all subjects and cross-sectional area and attenuation measured in Hounsfield units (HU) were determined for the trunk, gluteus, and mid-thigh muscles.ResultsCompared to Beijing, Kunming adults were slimmer (Beijing men vs Kunming men: 25.08 ± 2.62 vs 23.94 ± 3.10kg/m2, P=0.013; Beijing women vs Kunming women: 25.31 ± 3.1 vs 23.98 ± 3.54 kg/m2, P= 0.001) and had higher muscle density in the L2-trunk and gluteus maximus muscles after adjustment for age and BMI (L2-trunk muscles: Beijing men 29.99 ± 4.17 HU vs Kunming men 37.35 ± 4.25 HU, P&lt; 0.0001; Beijing women 27.37 ± 3.76 HU vs Kunming women 31.51 ± 5.12 HU, P&lt; 0.0001; Gluteus maximus muscle: Beijing men 35.11 ± 6.54 HU vs Kunming men 39.36 ± 4.39 HU, P= 0.0009; Beijing women 31.47 ± 6.26 HU vs Kunming women 34.20 ± 5.87 HU P=0.0375). Age was similar in both cohorts and no differences were observed in the gluteus medius and minimus muscle or the mid-thigh muscle, either in the area or density.ConclusionsCompared with Beijing, the adults in Kunming had higher muscle density of the gluteus maximus and L2 trunk muscles, showing that living at a higher altitude might be beneficial to muscle quality.

Evaluation of Lower Limb Muscle Electromyographic Activity during 400 m Indoor Sprinting among Elite Female Athletes: A Cross-Sectional Study

The purpose of this cross-sectional study was to analyze changes in normalized surface electromyography (sEMG) signals for the gastrocnemius medialis, biceps femoris, gluteus maximus, tibialis anterior, and vastus lateralis muscles occurring during a 400 m indoor sprint between subsequent curved sections of the track. Ten well-trained female sprinters (age: 21 ± 4 years; body mass: 47 ± 5 kg; body height: 161 ± 7 cm; 400 m personal best: 52.4 ± 1.1 s) performed an all-out 400 m indoor sprint. Normalized sEMG signals were recorded bilaterally from the selected lower limb muscles. The two-way ANOVA (curve × side) revealed no statistically significant interaction. However, the main effect analysis showed that normalized sEMG signals significantly increased in subsequent curves run for all the studied muscles: gastrocnemius medialis (p = 0.003), biceps femoris (p < 0.0001), gluteus maximus (p = 0.044), tibialis anterior (p = 0.001), and vastus lateralis (p = 0.023), but differences between limbs were significant only for the gastrocnemius medialis (p = 0.012). The results suggest that the normalized sEMG signals for the lower limb muscles increased in successive curves during the 400 m indoor sprint. Moreover, the gastrocnemius medialis of the inner leg is highly activated while running curves; therefore, it should be properly prepared for high demands, and attention should be paid to the possibility of the occurrence of a negative adaptation, such as asymmetries.

Comparison of Post Isometric Relaxation of Gluteus Maximus and Static Stretching of Hip Flexors on Pain and Functional Status in Patients with Anterior Innominate Dysfunction

Objective: To compare the effects of Post Isometric Relaxation (PIR) of gluteus maximus and Static Stretching (SS) of hip flexors on pain and functional status in patients with Anterior Innominate Dysfunction. Methodology: A quasi experimental trial was conducted on thirty six patients of Anterior Innominate Dysfunction. All were randomly allocated to post isometric relaxation group and static stretching group. Both groups were treated with 12 treatment sessions in 4 weeks at frequency of 3 sessions per week. Numeric Pain Rating Scale (NPRS) and Modified Oswestry Disability Index (MODI) were used to measure the treatment effect at baseline, after 2 weeks and after 4 weeks. Data was analyzed by SPSS 21. Results: Mean Age of Group A (PIR) was 34.28±7.76 and Group B (SS) was 35.72±7.16. Mean BMI of participants was 23.84±3.29. Across group, both post isometric relaxation and static stretching had shown significant results with P value <0.05. But within group, post isometric relaxation had shown more significant results as compared to static stretching with P value <0.05. Conclusion: Both treatment techniques; Post isometric relaxation and Static stretching are effective and produced significant difference in NPRS and MODI score to improve pain and functional status but PIR had shown more promising results in patients with anterior innominate dysfunction. Key words: Sacroiliac Joint Dysfunction (SIJD), Muscle Energy Technique (MET), MODI (Modified Oswestry Disability Index).

Effect of Visualization on Muscular Activation for Stability in Adolescent Ballet Students

The purpose of this study is to determine whether commonly used visualization techniques, whose results have been solely anecdotal, produce tangible, scientific results in muscular activation and improvement to ballet balances. Ballet training methods include imagery techniques however, much of this practice is solely based on the experience of the instructor and its results are anecdotal so that there are many gaps between research on imagery and dance instruction. Few published studies focus on the effect of the imagery training for dance students on either motor and nonmotor outcomes (Abraham, 2019). A survey will be administered to ballet instructors to determine the most used visualization cues for stability. Three adolescent female ballet students studying under said instructors will be asked to perform three balances. Surface electromyography data will be taken on the gluteus maximus, hip adductors, and abdominal oblique. The length of balance will also be taken. The dancers will then be exposed to a short visualization session or stimulus of anatomical images with arrows showing bodily adjustments and targeted muscles accompanied by verbal cues developed based on the instructor techniques from the survey. The same balances and data will be taken following the session. Results will be compared to the control data taken prior to the session to reveal whether the visualization training had significant results by determining statistically significant changes in balance times and changes in neuron spikes following spike analysis. Dancers will also be asked for qualitative feedback. Subject 2 yielded a significant increase in length of balance in all three types and the most consistent increase in neuron spikes in all of their muscles. This suggests a positive correlation between an increase in the degree of neuron activation or recruitment of those stability muscles and the ability for an individual to balance. This was also supported by increased confidence they felt in their balances after the visualization session. Subject 1 yielded no significant change in balance time before and after the visualization stimulus and the number of neuron spikes decreased after the session. This suggests that decreased activity in the tested muscles for stability resulted in lower balance times. This lack of muscular activation could be attributed to fatigue as reported by the dancer. The rest of the balances yielded significant increases in lengths of balance which were accompanied by increases in neuron spikes in the gluteus maximus and hip adductors for Degage a la Seconde and in the gluteus maximus for Releve en Retire. Subject 3 yielded insignificant changes in balance times for the first two types of balances but produced increases in the number of neuron spikes in most of the tested muscles in all of the balances. Reports from the dancer of being “less wobbly” the unexpected data to be attributed to an allocation to quality of the balance. The results on length of balances, number of neuron spikes, and confidence/reflection feedback obtained by this study supports the scientific validity of commonly-used visualization techniques in ballet by showcasing a higher degree of activation in the targeted stability muscles and longer average balance lengths should ensue following visualization training. Results also suggest that visualization techniques and stimuli for stability are the most effective when applied to learning unfamiliar movements. Further research could apply such visualization techniques to other movements, and even outside of dance.